1. Field of the Invention
The present invention relates to an electronic display device. More particularly, the present invention relates to an electronic display device that can selectively realize either a two dimensional planar image or a three dimensional stereoscopic image.
2. Description of the Related Art
Generally, stereoscopic display devices are configured to allow a user to perceive a three dimensional image by providing different images to the user's left and right eyes. Among stereoscopic display devices, an autostereoscopic display device that can allow the user to see the stereoscopic image without wearing equipment such as polarizing glasses has been known.
A typical autostereoscopic display device employs a method where a light-separation element such as a lenticular lens or a parallax barrier is positioned on a front portion of a display unit in order to separate from each other left eye and right eye images that are displayed on the display unit, and direct them toward the user's left and right eyes, respectively. However, the autostereoscopic display device has a drawback in that it can only display a stereoscopic image.
Therefore, in recent years, a liquid crystal (LC) parallax barrier using technologies relating to a liquid crystal display panel has been developed to selectively realize either a two dimensional planar image or a three dimensional stereoscopic image. The LC barrier includes a liquid crystal layer and electrodes that are provided between a pair of substrates, and polarizing plates attached on respective outer surfaces of the substrates. The LC barrier selectively realizes a two dimensional mode when it is in a total transmission state and a three dimensional mode when it is in an optically parallax barrier state.
However, in the conventional LC barrier, since the electrodes are patterned in the form of the parallax barrier, the manufacturing process is complicated. Further, since two glass substrates should be used, it is difficult to make the electronic display device slim. In addition, since a viewing distance (a distance between an electronic display device and a viewer) that allows the viewer to identify the stereoscopic image is relatively long as the left eye and right eye images are separated from each other by a distance between the left and right eyes, it is difficult to apply the liquid crystal barrier to a mobile device.
The viewing distance is proportional to a distance between an image formation plane of the display unit and an image separation plane of the LC barrier, and the image separation plane is generally formed in the LC barrier with reference to the liquid crystal layer. In order to reduce the viewing distance, a distance between the image formation plane and the image separation plane must be reduced. However, in the conventional LC barrier, there is a limitation in reducing the viewing distance due to the thicknesses of the glass substrates and the polarizing plate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.